In the movie Eternal Sunshine of the Spotless Mind, one of the main characters hires Lacuna, Inc., a company that specializes in erasing memories. The main character (Clementine) uses the company's abilities to erase Joel's memories of their relationship. While Lacuna Inc. is a fictional company, snail surgeons from McGill and Columbia University have successfully erased specific long-term memories--but on sea slugs--slowly making this a reality to humans.
Long-term memories are handled by synapses, the connections between neurons. The properties of these synapses are "responsible for the maintenance of the memory," wrote professor Samuel Schacher in an email. These properties can decrease or increase in strength, and that can affect how we retain memories. "We were able to reverse long-term changes in synaptic strength at synapses known to contribute to different forms of memories," says Schacher.
The researchers used a sea slug called Aplysia and erased certain types of long-term synaptic memories. They found that these memories are supported by two different type of PKM or Protein Kinase M molecules. And by blocking just one of these molecules, they can pick which memory to block.
"Looking at neural circuits, especially the identity of specific cells that encode a memory are not that simple, let alone examining whether they are changing in strength. So in this study we were able to reverse long-term changes in synaptic strength at synapses known to contribute to different forms of memories that last several weeks," Schacher wrote. However, the researchers aren't sure if the memories were erased permanently.
Also, erasing certain memories in humans would be trickier as the process of retaining a memory is far more complex. Certain sets of memories can even be intertwined, especially in the case of PTSD survivors . Part of this are those neutral things that aren't directly related to the traumatic event but were merely there, and hence, can trigger anxiety when faced with such object again. However, if successful, application of the research on humans can help with this as selective erasure of such incidental memory can be beneficial.
Further research is needed on how PKM molecules are made before scientists can see which drugs can block them. Since it's a long way off for Lacuna Inc. to be realized, guess we can instead just continue falling in love with Clementine and Joel's story over and over again.